Anyone know what might cause lumps on the back of my calves?

So, I've been training in BJJ since late July and am loving it so far. Great exercise, and my arms and chest turn such pretty colors! However, Ive noticed that after hard exertion I sometimes get clusters of small, soft lumps on the backs of my calves. They aren't painful or tender, or at least no more than the general muscle soreness you would expect. They also are usually gone a few hours later, and almost always by the time I get up the next morning.

Does anyone know what might be causing this? And is it something that I ought to be concerned about?

Could be cellulite. I am pretty sure cellulite is more prominent while you are still losing weight (or after dehydrated from a workout) and the calf muscles circulate blood very poorly and tend to build up pockets of cellulite that eventually even out as fat gets burned/absorbed.